How Does Interest Work on Unsubsidized Student Loans?

Interest on an unsubsidized student loan starts accruing the day your school receives the first disbursement, and it keeps running every day after that until the loan is paid off. The federal government does not cover any of it for you. So how does interest work on unsubsidized student loans in practice? A fixed annual rate is converted into a daily rate, applied to your outstanding principal each day, and periodically added to that principal at certain events — a process that can quietly grow what you owe long before your first required payment.

When Interest Starts and Why It Never Pauses

Your loan begins generating interest as soon as the money is disbursed to your school. It does not wait for you to graduate, drop below half-time enrollment, or enter repayment. Full-time, part-time, or sitting out a semester, the daily clock runs the same.

After you graduate or drop below half-time, most Direct Loans give you a six-month grace period before your first payment is due. Interest still accrues during that entire grace period. The same is true during deferment or forbearance: payments may be paused, but interest is not. A borrower who takes four years to finish a degree and then uses the full grace period will have roughly four and a half years of accumulated interest before making a single required payment.

How the Rate Is Set

Congress does not pick a new rate each year by hand. Federal law ties the rate for Direct Unsubsidized Loans to the 10-year Treasury note, using the yield from the last auction held before June 1. A fixed margin is added: 2.05 percentage points for undergraduate loans and 3.60 percentage points for graduate and professional loans. The resulting rate applies to every loan disbursed between July 1 and the following June 30, and it stays locked in for the life of that loan.¹

The law also sets a ceiling. Undergraduate unsubsidized loans are capped at 8.25%, and graduate unsubsidized loans are capped at 9.50%. Even if Treasury yields spike, your rate cannot exceed those limits.¹

For the 2025–2026 academic year, the fixed rate is 6.39% for undergraduate unsubsidized loans and 7.94% for graduate and professional unsubsidized loans.²

How the Daily Interest Is Calculated

Federal student loans use a simple daily interest formula. Your servicer divides the annual rate by the number of days in the year to get an interest rate factor, then multiplies that factor by your outstanding principal. The result is the interest that accrues that day.³

Here is the math on a $10,000 unsubsidized loan at the current undergraduate rate of 6.39%:

Interest rate factor: 0.0639 ÷ 365.25 = 0.0001749
Daily interest: $10,000 × 0.0001749 = roughly $1.75 per day
Over four years of school plus a six-month grace period: about $1.75 × 1,644 days = roughly $2,877 in accrued interest before the first required payment

That math is worth staring at. A student who borrows $10,000 as a freshman and never makes a voluntary payment will owe close to $12,900 by the time repayment starts. Multiple unsubsidized loans across several years each generate their own daily interest independently.

One more wrinkle at disbursement: before the money reaches your school, the federal government deducts an origination fee of 1.057% on Direct Unsubsidized Loans first disbursed between October 1, 2020 and October 1, 2026.³ On a $10,000 loan, about $106 is withheld, so your school receives roughly $9,894 — but interest is charged on the full $10,000.

How Your Payments Are Applied

When you pay, your servicer does not drop the money straight onto your principal. Payments first cover any outstanding fees and accrued interest. Only after interest is fully paid does the remainder reduce the principal. That is why minimum payments early in repayment feel like they barely move the balance: most of each dollar is clearing interest that has been piling up.

The order matters day to day. If you have $500 in accrued interest and make a $600 payment, only $100 reduces your principal. The next day’s interest is calculated on a principal that dropped by $100, not $600. Larger-than-minimum payments break the cycle, because once accrued interest is cleared, every additional dollar directly shrinks the balance that generates future interest.

Capitalization: When Interest Becomes Principal

Capitalization is the event that turns simple interest into something much more expensive. When unpaid interest capitalizes, it gets added to your principal balance. From that point on, you are charged interest on a larger amount, so the daily accrual also goes up.

For Direct Loans held by the Department of Education, capitalization happens at specific trigger points. Interest capitalizes when a deferment ends on an unsubsidized loan. It also capitalizes under certain income-driven repayment plan changes, such as when you voluntarily switch plans, miss your annual income recertification deadline, or no longer qualify for a reduced payment after recertification.⁴

The impact compounds. Using the earlier example, suppose a borrower accumulates $2,877 in interest during school and the grace period. When that interest capitalizes, the new principal becomes $12,877 instead of $10,000. Daily interest jumps from about $1.75 to about $2.25. Over a standard 10-year repayment period, that single capitalization event adds hundreds of dollars to the total cost because the higher principal keeps generating higher interest.

The Department of Education finalized regulations in 2023 that eliminated several capitalization triggers for borrowers on income-driven repayment plans. Court challenges have disrupted some of those changes, and the regulatory picture remains in flux. The triggers above reflect what servicers are currently applying, and checking with your specific servicer about what applies to your account is worth the phone call.

Keeping Interest Down

You are never required to wait until repayment begins to start paying. You can make payments on the interest that accrues while you are still enrolled and during the grace period.⁵ Even small monthly interest payments keep the balance from growing and eliminate the capitalization hit at the end of the grace period. On the $10,000 example, paying about $53 a month during school would cover the monthly interest at 6.39% and keep the balance from ever exceeding $10,000. Paying $25 a month still cuts the amount that eventually capitalizes roughly in half.

A few other moves make a measurable difference:

Borrow only what you need. You can accept less than the full amount offered, and every dollar you decline is a dollar that never generates interest.⁵
Shorten the grace period. If you land a job before the six-month grace period ends, you can ask your servicer to start repayment early. Each month you shave off is a month of interest that does not capitalize.⁶
Clear accrued interest before adding to principal. If extra money arrives, wiping out accrued interest first prevents capitalization and immediately lowers the base on which future interest is calculated.
Avoid forbearance when you can. Forbearance pauses payments but not interest, and interest capitalizes when forbearance ends. An income-driven repayment plan that keeps some payment flowing is usually better than a full pause.

The mechanics are not complicated — a daily rate, applied to a principal, with specific events that can grow that principal — but the cost of ignoring them is not small. A borrower who knows when interest accrues, when it capitalizes, and how payments are applied has what they need to keep thousands of dollars from quietly adding themselves to the balance.

1
Office of the Law Revision Counsel. 20 USC 1087e – Terms and Conditions of Loans
2
Federal Student Aid. Interest Rates for Direct Loans First Disbursed Between July 1, 2025 and June 30, 2026
3
Federal Student Aid. Federal Interest Rates and Fees
4
Nelnet – Federal Student Aid. Interest Capitalization
5
Federal Student Aid. Subsidized and Unsubsidized Loans
6
Federal Student Aid. Grace Periods, Deferment, and Forbearance in Detail – Chapter 3